Unfortunately, but Nintendo's Error Code Lookup for the 102-2802 error code doesn't give any explanation as to what the problem is and only suggests calling them, sorry.
So please call Nintendo's 1-800-255-3700 (6 am ~ 7 pm Pacific, everyday) Customer Service number, and one of the service representatives can do some over the phone troubleshooting to determine exactly what the problem(s) might be, and then talk you through any needed steps to correct this.